Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1485901 | Journal of Non-Crystalline Solids | 2006 | 4 Pages |
Abstract
Chain dynamics in hyperbranched polyimides based on 2,4,6-triaminopyrimidine and 4,4′-oxydiphthalic anhydride (molar ratio 1:1) cross-linked with ethylene glycol diglycidyl ether was investigated by means of broadband dielectric relaxation spectroscopy and thermally stimulated depolarization currents techniques. The secondary γ relaxation increases in magnitude and slows down with increasing degree of cross-linking, whereas the α relaxation, associated with the glass transition, becomes faster. These effects were explained in terms of increase of free volume and of constraints to the motion imposed by cross-links.
Keywords
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Physical Sciences and Engineering
Materials Science
Ceramics and Composites
Authors
Panagiotis Maroulas, Sotiria Kripotou, Petr Sysel, Radka Hobzova, Jiri Kotek, Polycarpos Pissis,